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Phylum Mollusca(5 Classes)
Polyplacophora – Many plates on a foot
Cephalopoda – Head foot
Gastropoda – Stomach
Scaphopoda – Tusk shell
Bivalvia – Hatchet foot
foot
Policemen Censor Gals in Scant Bikinis!
Typical questions for Mollusca
•How many of these specimens posses a radula?
•Which ones are filter feeders?
•Which have undergone torsion? Detorsion?
•Name the main function of the mantle?
•Name a class used for currency
•Which specimens have lungs? (Just have think of which live on land vs. in water……)
•Name the oldest part of a univalve shell? Bivalve?
Answers…maybe• Gastropods, Cephalopoda, Mono-, A- &
Polyplacophora
• Bivalvia (Scaphopoda….have a captacula)
• Gastropods Opisthobranchia (sea hares & sea slugs) and the land slugs of the Pulmonata
• Mantle secretes the shell
• Scaphopoda
• Pulmonata – their name gives this away
• Apex for Univalve, Umbo for bivalve but often the terms are used interchangeably
Chitons radula, 8 plates
Class Polyplacophora
Mantle
AnusGills in mantle cavity
Radula in mouth
Head
Class Cephalopoda - Octopuses, Squid, Nautilus,Cuttlefish…beak, pen, ink sac, chromatophores,jet propulsion……….dissection.
Tentacles (2) & arms are all derived from the gastropod foot
Gastropoda WORDS TO KNOW:
snails, conchs, torsion, coiling, radula, operculum & egg sac
Aquatic – marine.
Generally having thick pointed shells, spines, & many have opercula.
Subclass Pulmonata
Aquatic – freshwater.
Shells are thin, rounded, with no spines, ridges or opercula.
Apex
Subclass Prosobranchia
…….it issomething from Class Gastropoda
(…or your roommate!)
Subclass PulmonataSlug
Subclass Opisthobranchia
Nudibranch
Detorsion…
If something looks strange, chances are….
Class Gastropoda
‘POP’
Subclass Prosobranchia - Aquatic snails (“shells”)
- Have gills
Subclass Opisthobranchia- Marine
- Have gills
- Nudibranchs / Sea slugs / Sea hares
- Mantle cavity & shell reduced or absent
Subclass Pulmonata- Terrestrial Slugs and terrestrial snails
- Have lungs
Sinistral Dextral
Class Scaphopoda - “tusk shells”
Wampum Indian currency. ‘Head’ in sand. Respire through mantle (no gills.) Captacula for feeding on (capturing) foramniferans
ClaBivalvia or Pelecypoda - clams, scallops etc. filter feeders, bivalved shells…… dissection
D
VAP
Name of oldest part?
ClaBivalvia or Pelecypoda - clams, scallops etc. filter feeders, bivalved shells…… dissection
D
VAP
Umbo
Mouth
Labial palps
Ventricle
AuricleIntestine
FootMantle
Excurrent
& Incurrent siphon (-hairs & papullae)
Gills or ctenidium –
Each = 2 demibranchs
Anterior (Umbo)
Posterior
Dorsal (hinge)
Ventral
Percardial cavity
Visceral Mass
Stomach = Area of gastric & /digestive glands
Adductor muscle
Visceral mass – gonads & digestive tissues
FootMantle